Memory addressing structural test

Abstract

An apparatus and method for testing an address decoder and word lines of a memory array comprised of connecting a signature analyzer to the word lines emanating from an address decoder, setting a clock used to trigger the latching of the states of the word lines by the signature analyzer, transmitting an address to the address decoder to be decoded, and triggering the signature analyzer to latch the state of the word lines.

What is claimed is:  
     
       1. An apparatus, comprising: 
       an address decoder;  
       a plurality of word lines emanating from the address decoder;  
       at least one memory cell connected to at least one of the word lines; and  
       a signature analyzer connected to at least two of the plurality of word lines.  
     
     
       2. The apparatus of  claim 1 , wherein the address decoder decodes a portion of a memory address. 
     
     
       3. The apparatus of  claim 1 , wherein the at least one memory cell is a dynamic RAM memory cell. 
     
     
       4. The apparatus of  claim 1 , wherein the at least one memory cell is a static RAM memory cell. 
     
     
       5. The apparatus of  claim 1 , wherein the address decoder and the signature analyzer are connected to opposite ends of at least one of the plurality of word lines. 
     
     
       6. The apparatus of  claim 1 , wherein the signature analyzer latches the state of at least one of the plurality of word lines in response to a clock. 
     
     
       7. The apparatus of  claim 6 , wherein the timing of the clock is adjustable. 
     
     
       8. A method, comprising: 
       setting the timing of a clock used to trigger the latching of inputs to a signature analyzer;  
       transmitting an address to an address decoder connected to the inputs of the signature analyzer through a plurality of word lines;  
       decoding the address using the address decoder; and  
       triggering the signature analyzer with the clock to latch the state of the plurality of word lines connected to the inputs of the signature analyzer.  
     
     
       9. The method of  claim 8 , further comprising examining the output of the signature analyzer for each address decoded to determine if the correct word line was turned on, and to determine if any other word line was turned on for that address. 
     
     
       10. The method of  claim 8 , further comprising examining the output of the signature analyzer for a plurality of addresses decoded to determine if the correct word line was turned on, and to determine if any other word line was turned on for all of the plurality of addresses. 
     
     
       11. The method of  claim 8 , further comprising setting the timing of the clock to a plurality of different settings to determine which ones of the plurality of word lines operate more slowly. 
     
     
       12. The method of  claim 8 , further comprising setting the timing of the clock so that the plurality of word lines are tested at a desired operating speed. 
     
     
       13. An apparatus, comprising: 
       an address decoder;  
       a signature analyzer;  
       a plurality of circuits organized into a two-dimensional array comprising a first circuit, a second circuit, a third circuit and a fourth circuit;  
       a first word line coupled to the address decoder, the signature analyzer, the first circuit and the second circuit; and  
       a second word line coupled to the address decoder, the signature analyzer, the third circuit and the fourth circuit.  
     
     
       14. The apparatus of  claim 13 , wherein the address decoder decodes at least a portion of a memory address. 
     
     
       15. The apparatus of  claim 13 , wherein the first, second, third and fourth circuits are memory cells. 
     
     
       16. The apparatus of  claim 13 , wherein the first, second, third and fourth circuits are programmable logic devices. 
     
     
       17. The apparatus of  claim 13 , wherein the address decoder and the signature analyzer are connected to opposite ends of the first and second word lines. 
     
     
       18. The apparatus of  claim 13 , wherein the signature analyzer latches the state of at least one of the plurality of word lines in response to a clock. 
     
     
       19. The apparatus of  claim 18 , wherein the timing of the clock is adjustable.